@Override
 public final void setChild(int index, XcNode child) {
   if (index < _stmtAndDeclList.size()) _stmtAndDeclList.set(index, (XcStAndDeclObj) child);
   else throw new IllegalArgumentException(index + ":" + child.getClass().getName());
 }
 @Override
 public final void addChild(XcNode child) {
   if (child instanceof XcDeclsObj) _decls = (XcDeclsObj) child;
   else if (child instanceof XcStAndDeclObj) _stmtAndDeclList.add((XcStAndDeclObj) child);
   else throw new IllegalArgumentException(child.getClass().getName());
 }